我如何可以调用在LINQ to Entities查询本地方法？ [英] How can I call local method in Linq to Entities query?

问题描述

我有以下的code：

public void SalesCount(string customerId)
{
  ..
  ..
  return ...;
}

var resultQuery = dataContext.Customers
.Where (c => c.Name == "Alugili")
.Where (c => SalesCount(c.CustomerId) < 100);

当我执行resultQuery我得到一个转换为SQL例外。

When I execute resultQuery I get a translation to SQL exception.

我需要调用 SalesCount 在其中，我能做到这一点是有没有办法解决这个问题！

I need to call SalesCount in the Where can I do that is there any workaround for this problem!

推荐答案

只要你不能。不能在SQL服务器上执行C＃code直接，只能使用防爆pressions 和一些特殊功能的认可...

Simply you can't. You can't execute C# code on the SQL server directly, you can use only Expressions and some special recognized functions...

除非你改变你的查询（至少部分地）在LINQ到对象...

Unless you transform your query (at least partially) in a LINQ-to-Objects...

var resultQuery = dataContext.Customers
    .Where (c => c.Name == "Alugili")
    .AsEnumerable()
    .Where (c => SalesCount(c.CustomerId) < 100);

请注意，最后的其中，在客户端将被执行，那么多没用的行会从数据库中获取的。

Be aware that the last Where will be executed on the client side, so many useless rows will be fetched from the DB.

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